Positioning apparatus

Abstract

A positioning apparatus comprises a base element provided for fastening to a robot, a base movably supported at the base element, and a piezoactuator by which the base is movable in a direction relative to the base element. A second piezoactuator is provided by which a counterweight is simultaneously movable in an opposite direction.

Claims

1. An apparatus for positioning a tool, the apparatus comprising: a base element provided for fastening to a robot; a base movably supported at the base element; at least one first piezoactuator by which the base is movable in a first direction relative to the base element; at least one second piezoactuator by which a first counterweight is simultaneously movable in the direction oppositely disposed to the first directions; at least one third piezoactuator by which the base is movable in a second direction relative to the base element; at least one fourth piezoactuator by which a second counterweight is simultaneously movable in a direction opposite to the second direction; at least one fifth piezoactuator by which the base is movable in a third direction relative to the base element; and at least one sixth piezoactuator by which a third counterweight is simultaneously movable in a direction opposite to the third direction.

2. The apparatus in accordance with claim 1, wherein the tool is a metering apparatus.

3. The apparatus in accordance with claim 1, wherein all three directions extend at right angles to one another.

4. The apparatus in accordance with claim 1, wherein the base is pivotably arranged at the base body.

5. The apparatus in accordance with claim 4, wherein the base is pivotable about two axes that are perpendicular to one another.

6. The apparatus in accordance with claim 1, wherein at least two piezoactuators are fastened to the base element.

7. The apparatus in accordance with claim 6, wherein all the piezoactuators are fastened to the base element.

8. The apparatus in accordance with claim 1, wherein the movement of at least one piezoactuator is transmitted to the base via a connecting rod.

9. The apparatus in accordance with claim 1, wherein at least two piezoactuators are of the same construction.

10. The apparatus in accordance with claim 1, wherein at least two piezoactuators are connected in opposite polarities to one and the same control output of a control.

11. The apparatus in accordance with claim 1, wherein at least two counterweights have masses of different amounts.

12. The apparatus in accordance with claim 1, wherein the base has a metering valve that is actuated by a plunger that is movable by a metering drive.

13. The metering apparatus in accordance with claim 12, wherein the metering drive is movable in a direction together with the base.

Description

(1) The invention will be described in the following purely by way of example with reference to an advantageous embodiment and to the enclosed drawing. There are shown:

(2) FIG. 1 a perspective view of a positioning apparatus in accordance with the invention;

(3) FIG. 2 a section through the positioning apparatus of FIG. 1;

(4) FIG. 3 a detail of the view of FIG. 1;

(5) FIG. 4 a detailed view of a metering valve of the metering apparatus of FIG. 1; and

(6) FIG. 5 a further embodiment of a counterweight.

(7) FIGS. 1 to 4 show an apparatus for positioning a tool. A metering apparatus 10 for placing drops of a medium to be metered, a solder paste here, on a substrate is shown as an example for a tool in the Figures. Other tools can, however, also be considered, for example optical or electrical test apparatus or the like.

(8) The positioning apparatus comprises a base element 12 provided for fastening to a robot, not shown, and a base 14 fastened to the base element 12. In the embodiment shown, the base 14 is formed as a metering apparatus 10.

(9) The base 14 is movable and is in particular pivotable in a first direction X, in a second direction Y, and in a third direction Z relative to the base element 12. For this purpose, the base 14 is gimballed at an articulation point 15 such that the base 14 can be pivoted both about the axis A1 and about the axis A2 (FIG. 3).

(10) A piezoactuator 16 is provided for a movement of the base 14 in the X direction and is connected to the base 14 via an arm extension 17 by means of a connecting rod 40. The lower end of the boom 17 is moved to and fro in the X direction by actuating the piezoactuator 16 so that the front end of the base 14 is interlocked about the axis A2. It must be noted here that the stroke of the piezoactuator 16 is in an order of magnitude of approximately 200 m, i.e. the deflections are very small. Due to the large lever arm between the articulated point 15 and the front end of the base 14, the front end of the base 14 moves in an almost linear manner in the region of the actual deflections.

(11) To compensate the movement of the base 14 by the piezoactuator 16, a further piezoactuator 18 is fastened to the base element 12 and likewise has an arm extension 19 to whose lower end a counterweight 20 is fastened. The two piezoactuators 18 are connected in opposite polarity to one and the same control output of a control, not shown, so that on a movement of the connecting rod 40 in the X direction, the counterweight 20 performs the same movement in the X direction. No changing load is hereby produced at the robot if the base 14 with the metering device is frequently alternately moved to and fro.

(12) As FIG. 4 shows, a piezoactuator 22 and a connecting rod 42 are provided for the movement of the base 14 in the Y direction, with a piezoactuator 26 at which a counterweight 24 is fastened being provided to compensate the movement. The design is the same as the one described above.

(13) To be able to move the base 14 in the Z direction, it is connected via two connecting rods 44 and 46 to an arm extension 60 that can in turn be moved by two piezoactuators 28 and 30 in the direction of the double arrow 61 shown (FIG. 3), whereby the base 14 is pivotable about the axis A2. To compensate this movement, a third counterweight 36 is provided at the base element 12 and is pivotable via two piezoactuators 32 and 34 in the opposite sense to the movement of the piezoactuators 28 and 30. Since the respective piezoactuator for the movement of the base 14 and the piezoactuator for the counter-movement of the counterweight are of the same construction and are controlled with mirror symmetry, a best possible compensation of the movement is achieved.

(14) As FIG. 2 illustrates, the base 14 is formed as a metering device and a metering valve 50 that can be opened and closed by the plunger 52 is located in the base 14. A hose 65 is provided to supply the medium to be metered.

(15) FIG. 5 shows an alternative embodiment for the drive of the plunger 52, with not one counterweight being provided in this embodiment, but rather two counterweights 70 and 72 that can be moved symmetrically with respect to both sides of the plunger 52.

(16) The base 14 is moved via the four connecting rods 40-46 with the connecting rods 44 and 46 performing a parallel movement in the Z direction and with the drives 16 and 22 in X and Y respectively pushing the position of the nozzle of the valve in this direction.

(17) The design is configured such that the movement of the front end of the base 14 in X, Y, and Z is respectively produced by a slight rotation about a remote fixed point 15. Only a portion of the mass of the base has to be moved for the movement of the valve in X, Y, and Z due to this design. The fixed point 15 additionally makes it possible that the supply hose 65 for the valve 50 can here be conducted to a cartridge with a very small deformation by the movement.

(18) It is advantageous to separate the drive and the tool and to transmit the movement by connection rods. It is also advantageous to produce the movement in X, Y, and Z by a slight rotational movement. If the tool or the base 14 is then designed as elongate so that the center of mass is remote from the location of the positioning (metering nozzle), only a little work in turn has to be carried out for the movement. The drives of the individual axes and the drives of the counterweights are respectively exactly the same. The control can then take place in a very simple manner in that the two drives are connected to the same control output with opposite polarity.